Clinical Case Challenge: Cervical Abscess in a Dog

History    

A 7-year-old, neutered male Labrador retriever is presented on an emergency basis for a swelling in the ventral mid-cervical region that developed over the past week. On physical examination, the swelling was about 8 cm in diameter, slightly painful, and firm on palpation. The dog seemed otherwise normal.

What are your rule-outs for this case?

Cervical abscess – Cervical abscesses often develop in dogs that chew sticks, and the problem is common in New England. A small piece of the stick breaks off, penetrates the oral mucosa, slowly migrates into the neck, and eventually causes an abscess. Acute abscesses may be well-defined and relatively soft. More chronic abscesses may feel diffuse, poorly-defined, and firm. Cervical abscesses may be accompanied by fever and depression.

Salivary mucocele – Salivary mucoceles usually result from idiopathic leakage of saliva from the sublingual salivary duct on one or both sides. They may occur in the upper neck (cervical mucocele), beneath the tongue (sublingual mucocele, or ranula), or on the lateral wall of the pharynx (pharyngeal mucoceles). Cervical mucoceles are by far the most common, and usually are located near the mandibular and sublingual salivary glands on the affected side, but can be located near the midline of the neck. The swelling is generally soft, obviously fluid-filled and non-painful, and causes no systemic signs. The treatment is removal of the mandibular and sublingual glands on the affected side.

Tumor – Malignancies that may occur in the cervical region include thyroid carcinoma, lymphoma, mast cell tumor and soft tissue sarcoma. These generally feel mass-like and are firm but somewhat moveable.

What would be your next steps?

You perform a fine needle aspirate of the mass, remove several milliliters of purulent fluid, and examine it cytologically.

What is the cytologic diagnosis for each of the following images? Answers

A - The smear is relatively acellular, and there is a significant amount of background purple-staining mucus.

B – Sarcoma – Spindle cells with large nuclei predominate, indicative of a soft tissue sarcoma.

C – Infection – There are numerous lymphocytes and degenerate neutrophils, with rod-shaped bacteria near the center of the slide.

Diagnosis and Treatment

You diagnose a cervical abscess and recommend surgery. Your plan is to make a small incision, open the abscess, explore it for a foreign body, obtain a culture, lavage it and place closed-suction drains.

What are three advantages of closed suction drains over passive drains such as Penrose drains?

Drainage is more complete (Penrose drains rely on capillary action and gravity, whereas closed suction drains are active – suction is applied by the reservoir bag); drainage can be quantified (this allows an informed decision regarding when it is time to remove the drains – most drains are removed at 2-3 days); the risk of ascending infection is lower; and closed drains are neater (fluid collects in the reservoir, not on the dog).

At surgery, you explore the interior of the abscess and are unable to find a foreign body. This is typical, as the foreign material is usually completely degraded by the body’s inflammatory response. Drainage dramatically decreases after two days, you remove the drains, and the abscess permanently resolves.

A narrated video demonstrating placement of closed suction drains in a dog with a cervical abscess is shown below.